1. Field of the Invention
The present invention concerns an automatic switching procedure for headlights, designed to emit a beam of light for motor vehicles from one lighting mode to another lighting mode, and an automatic switching device that enables the commissioning of the procedure.
It is particularly applied in the field of automobiles.
2. Description of the Related Art
In the field of automobiles, a previous state of technology known as an automatic headlight switching procedure for motor vehicles, designed to emit a beam of light from one lighting mode to another lighting mode, makes it possible to automatically switch the headlights of the motor vehicle:                on the one hand from a low beam position (headlights on low beam) to a full beam position (headlights on full beam) when the vehicle is located in an unlit environment and without there being any crossed or followed vehicle in front (first switching);        and on the other hand from a full beam position to a low beam position when there exists a phenomenon of visibility disturbance such as fog (second switching) or again when the vehicle is located in a lit environment, with or without the presence of a phenomenon of visibility disturbance, or again when there is a crossed or followed vehicle in front, whether or not a phenomenon of visibility disturbance is present. If a phenomenon of visibility disturbance is present, the phenomenon of visibility disturbance is detected, and switching takes place, on the basis of a backscatter phenomenon of the headlight beam which results from the combination of the lighting of the headlights and the phenomenon of visibility disturbance. If the backscatter is too great, then switching takes place.        
This avoids the vehicle driver being disturbed by this backscatter phenomenon. Thus, thanks to this second switching, the backscatter phenomenon is attenuated, indeed annulled, so that the driver is no longer disturbed and therefore does not lose any road visibility. Furthermore, alongside this second switching, the first switching is prohibited. It will be authorized once visibility conditions have improved.
One disadvantage of this previous state of technology is that in the lighting mode in low beam position, with a low, indeed non-existent backscatter phenomenon, it is more difficult to detect the phenomenon of visibility disturbance than in full beam position. Also, when the phenomenon of visibility disturbance is attenuated or disappears, that is, when visibility conditions improve, such a procedure does not allow it to be detected and the first switching is not reactivated. The headlights remain on low beam position, while according to circumstances it could be necessary to return to full beam position.
There is, therefore, a need to provide an improved switching procedure and device.